Magnetic catch



M. O. TEETOR MAGNETIC CATCH Sept. 27, 1955 Filed Aug. 30 1951 22 INVENTOR. g 0 Teefo 7;

Ma BY i7M,fi-L7 United States Patent MAGNETIC CATCH Macy 0. Teetor, New Orleans, La. Application August 30, 1951, Serial No. 244,417

2 Claims. (Cl. 292-2515) This invention relates to a device utilizing magnetic principles for retaining a closure member in closed position adjacent a frame member and more particularly to a magnetic catch for use on a cabinet door.

Magnetic door catches of various types have been suggested heretofore in which cooperating magnet and armature units are mounted in coacting positions on a pair of door and frame members. In most cases, the magnetic attractive forces are exerted in a direction transverse to the plane of the hinged door so that as the door approaches closed position the magnet unit exerts a positive force tending to move the door to closed position. In other words, in an installation of this type the magnet unit may actually assist in effecting closure of the door as well as retaining the door in closed position.

The present invention is directed more particularly to a magnetic catch in which the magnet and armature units are mounted in coacting relation adjacent the vertical edgewise surface of the door so that the magnetic attractive forces act in a lateral direction substantially in the plane of the door. As will hereinafter appear, in a device of the latter type the catch acts primarily to retain the door in closed position by reason of the frictional surface contact and resistance between the magnet and the armature elements. In a catch installation of this type relatively slight frictional resistance is suflicient to retain the door in closed position and consequently the catch parts can be relatively small and inexpensive. A magnetic catch of the present type is particularly well suited for use on radio cabinet doors and the like.

A primary object of my invention is to provide a magnetic door catch of simple and inexpensive design which is adapted to retain the door in closed position primarily by frictional surface contact between the operating parts of the catch.

A further object of the invention is to provide a magnetic catch of the character described which is particularly adapted for installation in the vertical edge portion of a door and the adjacent coacting portion of the door frame.

Another object of the invention is to provide a magnetic catch of the character described which is adapted to operate satisfactorily with varying clearances between the edge of the door and the adjacent surface of the door frame.

Other objects and advantages of the invention will be come apparent from the subsequent detailed description taken in conjunction with the accompanying drawing wherein:

Fig. l is a fragmentary front elevational view of a cabinet provided with a magnetic door catch embodying the features of the present invention;

Fig. 2 is an enlarged fragmentary end view of one portion of the catch illustrated in Fig. l;

Fig. 3 is a fragmentary horizontal sectional view on an enlarged scale, as taken along the line 33 of Fig. l, and showing the position of the catch elements when the door is closed;

Fig. 4 is a vertical sectional view taken along the line 44 of Fig. 2 and showing the position of one element of the catch with the door in open position; and

Fig. 5 is a view similar to Fig. 3 but showing a modified form of the invention.

Referring first to Fig. 1 of the drawing, a cabinet is shown comprising a door 10 hingedly secured to a frame having vertical portions 11 and 12 and a sill or base 13. An elongated strip or door stop 14 is provided on the base 13 in inwardly recessed relation from the front thereof, the door 10 being adapted to abut the strip 14 when the door is in closed position.

A magnetic catch is provided embodying the features of my invention and consisting of a magnet unit, indicated generally at 16, and a cooperating armature unit, indicated generally at 17. The magnet and armature units are mounted in coacting positions in the free vertical edge of the door 10 and the adjacent surface of the frame portion .12, respectively, so that the armature unit 17 can coact with the magnet unit 16 when the door 10 is in closed position against the door stop 14. As will hereinafter appear, the armature unit 17 is generally of slightly greater dimensions than the magnet unit 16 so that as a matter of convenience the armature unit is best suited for installation in the side portion 12 of the door frame with the magnet unit 16 being secured in the door 10. However, it is also within the scope of my invention to reverse the respective mountings of the magnet and armature units so that the magnet unit is located on the frame and the armature unit is located in the door.

Referring now to Figs. 2 to 4, the magnet unit 16 is shown as comprising a cylindrical permanent magnet element 18 having flat end faces and rigidly secured, as by a press fit, in a complementary bore 19 extending inwardly on a horizontal axis from the vertical edge of the door. As best seen in Fig. 3, the axial depth of the bore 19 is such that the outer end of the magnet 18 is substantially flush with the edgewise surface of the door, indicated at 20. A magnetic metal or alloy, such as the alloy of aluminum, nickel, and cobalt commercially available under the trade-mark Alnico, is particularly suitable for the magnet element 18. The magnet may be provided with a magnetic pole at each end, or both magnetic poles may be provided at the outer end of the magnet. In addition, the magnet element 18 may be conveniently and inexpensively formed by cutting off pieces of suitable length from an elongated bar magnet, or the magnet elements can be cast individually or fabricated from powdered ingredients.

The armature unit 17 comprises a tubular or cylindrical casing or housing 21 which is rigidly mounted in a horizontal bore 22 in the frame portion 12, the magnet-receiving bore 19 and the armature-receiving bore 22 being substantially coaxial when the door is in closed position. The outermost annular end of the housing 21 is turned radially inwardly to provide a retaining flange 23 which is substantially flush with the outer surface, indicated at 24, of the frame member 12. The inner end of the casing 21 is preferably provided with a similar inwardly extending flange 25 which engages the bottom of the bore 22. A movable armature element in the form of a generally cylindrical, and preferably cup-shaped, element 26 is disposed concentrically within the housing 21 and is of restricted diameter to permit the element 26 to extend outwardly through the opening in the flange 23 0f the housing 21 in the manner illustrated in Fig. 3. The inner end of the armature element 26 is formed with an outwardly extending flange 27, and a coil spring 28 is disposed concentrically in the annular clearance between the housing 21 and the armature element 26 with the opposite ends of the spring coacting with the flanges 23 and 27 for normally urging the armature element 26 into retracted position within the housing 21.

As will be seen in Fig. 4, when the door 10 is open so that the magnet 18 is disposed beyond the region where it can exert any influence upon the movable armature element 26, the spring 28 functions to retain the arma ture element 26 within the housing 21 with the flange portion 27 of the armature element abutting the inner flange 25 of the casing 21. The outer end of the armature element 26 is preferably completely closed, as at 29, and when in retracted position the closed end 29 of the armature element is substantially flush with the outer flange 23 of the armature housing 21 and also with the surface 24 of the frame member 12. Thus it will be seen that the armature unit presents a neat and attractive flush appearance (Fig. 2) when the door is in open position away from the frame.

When the door it) is moved into closed position against the door stop 14, it will be understood that the movable armature element 26 moves outwardly from the frame portion 12 until the closed end 29 of the armature element engages the outer end of the magnet 18 in frictional surface contact therewith, as illustrated in Fig. 3. This engagement between the magnet and armature elements under the magnetic attractive forces of the magnet 13 provides a substantial frictional resistance against pivotal movement of the door 10 so that the latter is securely held in closed position. In addition, the magnetic attractive forces are exerted laterally of the door and substantially in the plane thereof so that the door is held to a considerable extent against rattling movement.

When it is desired to open the door, a relatively slight manual pull will serve to effect sliding movement of the contact surface of the magnet 18 relative to the contact end 29 of the armature element until the magnet is completely disengaged from the armature element whereupon the armature element is retracted into its casing by the action of the spring 28. Because of the retractive function of the spring 28, the armature element 26 cannot possibly interfere with the normal operation of the door since the armature element 26 will remain in its normally retracted position until the magnet element 18 is moved into partial alignment or overlapping relation with the outer end of the armature element thereby permitting the attractive forces of the magnet 18 to act on the armature element. in other words, the armature element 26 can never move out prematurely and cause the door to strike the armature element because the magnet 13 will not effect axial shifting of the armature element until some substantial portion of the outer end of the magnet overlies the corresponding end 29 of the armature element.

Inasmuch as the movable armature element 26 moves outwardly from the housing 21 merely until frictional surface contact is made with the magnet 18, it will be seen that the device is adapted for use with door and frame assemblies having varying degrees of spacing or clearance between the surfaces 20 and 24. Thus, within practical limits, no special care is required in this regard.

Because of the simplicity of the construction of my device, it will be seen that the catch can be manufactured easily and inexpensively thereby making the device particularly suitable for mass production cabinet installations. Because the retaining action of the catch on the closed door is based primarily on the frictional resistance between the coacting surfaces of the magnet and armature elements, it will be understood that the respective elements may be of relatively small dimensions. The preferred cup-shaped structure of the armature element 26 is an important feature in this respect since it provides a light weight movable armature element which is readily actuated by the magnet and which does not require a magnet of excessive size. The armature element and its housing may be readily fabricated from sheet metal by conventional stamping techniques. The movable armature element is, of course, made of steel or similar magnetically permeable metal, and the armature housing may be of any suitable metal such as steel, brass, or aluminum, or even plastic. The coil spring may conveniently be formed from phosphorus bronze spring wire or the like.

The location of the magnetic catch adjacent the vertical edge of the door and the corresponding portion of the door frame whereby the armature element moves in a horizontal plane has several important advantages. In the first place, it will readily be seen that the catch is thereby mounted at the greatest possible distance from the hinges of the door at which point frictional resistance between the catch elements is most effective. Moreover, movement of the armature element in a horizontal direction is more readily accomplished with a relatively small magnet and a relatively small spring since vertical movement from either the top or the bottom of the door frame would require either a larger magnet or a stronger spring to compensate for the weight of the armature element. In addition, the mounting of the armature unit for horizontal movement in the vertical portion of the door frame eliminates to a large extent the tendency for dirt to collect inside the armature casing with consequent interference with the operation of the movable armature element.

In Fig. 5 I have shown a slight modification of the catch wherein the magnet element, indicated at 31, is provided with a relatively shallow axial cavity or bore 32 at its outer end and the movable armature element, indicated at 33, has a coacting rounded bulge or hump 34 extending outwardly at its outer end. As seen in Fig. 5, when the armature element is in extended position for retaining the door in closed position by frictional surface contact with the magnet, the convex bulge 34 of the armature is received within the complementary depression or bore 32 of the magnet while the surrounding flat annular faces of the magnet and armature elements are in full surface contact. This arrangement provides a somewhat greater frictional resistance for retaining the door in closed position and is particularly important in the case of relatively small magnets wherein the area of surface contact with the armature is at a minimum. Because of the rounded or convex contour of the bump 34, it will be understood that the armature element 33 is readily cammed into disengaged position during opening movement of the door 10.

Although the invention has been described herein in connection with certain specific structural embodiments, it will be understood that various equivalent structures and modifications may be resorted to without departing from the scope of the invention as defined in the appended claims.

I claim:

1. In a magnetic catch for holding a closure member in closed position adjacent a frame member, armature means adapted to coact with a companion magnet and comprising a cylindrical casing having inwardly directed integral flange portions at its opposite ends and adapted to be received and rigidly retained in a horizontally extending recess in a vertical portion of one of said members, a cup-shaped armature element disposed concentrically within said casing for axial movement therein and having a closed outer end and an outwardly directed integral flange portion at its inner end adapted to seat against the inner flanged end of said casing, and a coil spring disposed concentrically between said housing and said armature element, said spring coacting at its opposite ends with the outer flanged end of said casing and the inner flanged end of said armature element for normally urging said armature element into retracted position with the flanged inner end of the armature element abutting the flanged inner end of said casing, the axial depth of said casing and the axial depth of said armature element being such that when the armature element is in retracted position within said casing, the outer closed end of said armature element is in substantially flush alignment withthe outer flanged end of said casing.

2. In a magnetic catch for holding a closure member in closed position adjacent a frame member, armature means adapted to coact with a companion magnet and comprising a cylindrical casing having inwardly directed integral flange portions at its opposite ends and adapted to be received and rigidly retained in a horizontally extending recess in a vertical portion of one of said members, a cup-shaped armature element disposed concentrically within said casing for axial movement therein and with an annular clearance therebetween and having a closed outer end and an outwardly directed integral flange portion at its inner end adapted to seat against the inner flanged end of said casing, and a coil spring disposed concentrically between said housing and said armature element, said spring coacting at its opposite ends with the outer flanged end of said casing and the inner flanged end of said armature element for normally urging said armature element into retracted position with the flanged inner end of the armature element abutting the flanged inner end of said casing, the axial depth of said casing and the axial depth of said armature element being such that when the armature element is in retracted position within said casing, the outer closed end of said armature element is in substantially flush alignment with the outer flanged end of said casing, and said clearance permitting limited cocking and twisting movement of the armature element for facilitating alignment of the contact surface of the armature element at the outer closed end thereof with the contact surface of the companion magnet.

References Cited in the file of this patent UNITED STATES PATENTS 163,635 Calkins May 25, 1875 2,203,580 Ronning June 4, 1940 2,219,186 Hornfeck Oct. 22, 1940 2,475,226 Ellis July 5, 1949 2,497,697 Smith Feb. 14, 1950 2,530,628 Pivero Nov. 21, 1950 

